Transducer employing wireless transmissions for sending and receiving signals

• US 20050150286A1
• Filed: 12/03/2004
• Published: 07/14/2005
• Est. Priority Date: 01/12/2004
• Status: Active Grant

• Current Assignee: Kulite Semiconductor Products Inc
• Original Assignee: Kulite Semiconductor Products Inc
• Inventors: Kurtz, Anthony D., Landmann, Wolf S.
• Granted Patent: US 7,283,922 B2
• Time in Patent Office: Days
• US Class Current: 73/146.500
• CPC Class Codes: B60C 23/0413 Wireless charging of active radio frequency circuits
• CPC Class Codes: B60C 23/0433 Radio signals

Abstract

A transducer is implemented to operate with transmitted frequency signals. These transmitted signals provide a bias potential to the transducer and enable the transducer to transmit a transducer output signal to a remote location. The transducer has an antenna for receiving transmitted signals. The antenna is coupled to a rectifier circuit; the rectifier circuit is operative to provide a DC voltage in response to said received transmitted signals. This DC voltage is applied to the piezoresistive array via a switching arrangement coupled between the array and the rectifier circuit. An interface circuit controls the switching arrangement to enable DC bias to be applied to the array in a first mode and to remove the bias in a second mode.

Claims

1. A transducer adapted to respond to transmitted signals of a given frequency for providing a bias potential to said transducer and for enabling said transducer to transmit a transducer output signal to a remote location, comprising:

an antenna for receiving transmitted signals;

a rectifier circuit coupled to said antenna and operative to provide a DC operating voltage in response to said received transmitted signals;

a piezoresistive array operative to provide an output signal indicative of an applied pressure when said array is biased;

first switching means coupled to said rectifier circuit and said array and operative in a first mode to apply said DC operating bias to said array, and operative in a second mode to remove said operating bias;

an interface circuit coupled to said switching means and said array for operating said switching means in said first mode during the presence of receive transmitted signals to cause said array to provide said output signal and for applying said output signal to said antenna for transmission of said output signal to said remote locations, said interface circuit operative to operate said first switching means in said second mode when said transmitted signals are not received.

2. The transducer according to claim 1 wherein said transmitted signals are in the RF frequency range.

3. The transducer according to claim 1 wherein said interface circuit is coupled to said rectifier circuit to receive an operating bias from said rectifier circuit.

4. The transducer according to claim 3 wherein said interface circuit monitors said rectifier output to operate said first switching means in said first mode when said DC voltage exceeds a given value.

5. The transducer according to claim 1 wherein said antenna is a tuned antenna comprising an inductor in parallel with a capacitor and is tuned to the frequency of said transmitted signals.

6. The transducer according to claim 1 wherein said piezoresistive array is a Wheatstone bridge array.

7. The transducer according to claim 6 further including a span resistor coupled to said Wheatstone bridge to monitor bridge temperature.

8. The transducer according to claim 6 wherein the output of said bridge is coupled to said interface circuit, said interface circuit including an analog to digital converter for converting the bridge output signal to a digital signal, and a modulator responsive to said digital signal for modulating a radio frequency signal for transmission by said antenna to said remote location.

9. The transducer according to claim 8 wherein said radio frequency signal is at a frequency slightly different then the frequency of said transmitted signals.

10. The transducer according to claim 7 wherein said span resistor is coupled to said interface circuit to enable said circuit to convert the voltage across said span resistor into a radio frequency signal indicative of temperature.

11. The transducer according to claim 1 wherein said antenna is a tuned circuit antenna comprising an inductor in parallel with a first and second capacitor in series with a common terminal between said capacitors,

a second switching means having one terminal coupled to said common terminal and the other terminal coupled to a source of reference potential, wherein in a first mode said second capacitor is shorted by said switching means to cause said antenna to be tuned to a first frequency, and in a second mode said switching means is opened to cause said first and second capacitors to tune said antenna to a second different frequency;

said second switching means coupled to said interface circuit for controlling said second switching means in said first or second modes.

12. The transducer according to claim 11 wherein said interface circuit operates said second switching means to transmit transducer information to said remote location.

13. The transducer according to claim 1 further including a memory for storing conservation coefficients for said piezoresistive array.

14. The transducer according to claim 13 wherein said memory is an EEPROM.

15. The transducer according to claim 1 further including means for transmitting a transducer acknowledgement signal.